(1) Field of the Invention
This invention relates to a process and apparatus for producing a conductive damper for use in a speaker, in which knitted tinsel wires are integrated with the damper.
(2) Description of the Related Art
So far, a conductive damper for use in a speaker, which is formed by integrating knitted tinsel wires with the damper by means of sewing, glueing, knitting and so on, has been molded by putting the workpiece between an upper and lower molds followed by pressing under heating, similarly to an ordinary damper.
Consequently, depending upon the dimensions and configuration of a corrugation to be molded, there have been problems such that an excessive force is applied to the workpiece (a piece of cloth material) upon press molding, a non-uniform force is applied to the workpiece, threads in the workpiece are extended on an undesirable condition, and in an extreme instance the workpiece is torn up beyond its limits.
As to the conventional conductive damper for use in a speaker, in which knitted tinsel wires are integrated with the damper, since the knitted tinsel wires are sandwiched at a stretch by molds having the configuration of the corrugation, the knitted tinsel wires are damaged by a tension produced upon press molding, causing a deterioration in endurance against oscillation of a speaker. When the configuration of the corrugation is deep, the knitted tinsel wires are cut, making the press molding impossible.
It is therefore an objective of the present invention to solve the above problem and provide a process and apparatus for producing a conductive damper for use in a speaker, in which a double mold for press molding is employed in order to minimize the damage of the knitted tinsel wires by a tension produced upon press molding, that is, the corrugation of the damper is formed by using the two molds, an inner part of the corrugation is press-molded first, then an outer part of the corrugation is press-molded after a very short period of time so as to improve the endurance of the damper, and the press molding of the corrugation having a deep configuration is enabled to meet with the demand of producing a speaker having large oscillation amplitude.
In order to attain the above objective, the present invention is to provide a process for producing a conductive damper for use in a speaker, in the process a workpiece of the conductive damper, in which knitted tinsel wires are integrated with a sheet-shaped workpiece, is set between top and bottom molds, on the surface of each of which a plurality of corrugations are formed concentrically, then the workpiece of the conductive damper is pressed by the top and bottom molds so as to be molded in a damper-shape, the process comprising: a first step, in which the workpiece of the conductive damper is set on the bottom mold; a second step, in which the top mold is moved in the direction nearer to the bottom mold so as to mold one corrugation or a plurality of corrugations for the inner part of the workpiece of the conductive damper; and a third step, in which the top mold is further moved in the direction nearer to the bottom mold so as to mold one corrugation or a plurality of corrugations for the outer part of the workpiece of the conductive damper, wherein the third step is repeatedly performed so that the workpiece of the conductive damper is molded in a damper-shape.
The third step is performed once and the second step is performed twice.
By pressing the workpiece of the conductive damper at least in two steps separately, the large amount of cloth and knitted tinsel wires can be pulled into the mold compared to a conventional pressing. Thereby, the tensional damage applied to the knitted tinsel wires is reduced and the endurance of the conductive damper improves. Moreover, the press molding of the corrugation having a deep configuration is achieved to meet with the demand of producing a speaker having large oscillation amplitude.
The present invention is also to provide an apparatus for producing a conductive damper for use in a speaker, including top and bottom molds, on the surface of each of which a plurality of corrugations are formed concentrically, by using the apparatus a workpiece of the conductive damper, in which knitted tinsel wires are integrated with a sheet-shaped workpiece, is set on the bottom mold, then the workpiece of the conductive damper is pressed by moving the top mold so as to be molded in a damper-shape, the apparatus comprising: a bottom mold, on the surface of which a plurality of corrugations are formed concentrically; at least two divided top molds including a first top mold and a second top mold, which are formed by concentrically dividing the top mold into the inner part and the outer part and provided with a plurality of corrugations at positions corresponding to the corrugations of the bottom mold; and a moving mechanism moving up and down independent of the first and second top molds, including: a base, to which the second top mold is mounted; guiding means provided to the base for controlling a movement of the first top mold in the up-and-down direction; and energizing means provided to the base for energizing the first top mold to press the second top mold, wherein by moving the base downward, the inner part of the workpiece of the conductive damper is press-molded between the first top mold and the bottom mold, then the outer part of the workpiece of the conductive damper is press-molded between the second top mold and the bottom mold.
The first top mold is divided concentrically into a plurality of divided molds, each of which has the guiding means and the energizing means.
According to the construction described above, the base is moved downward to allow an inner top mold (i.e. the first top mold) to abut on the bottom mold, then the base is further moved downward to allow the inner top mold and the bottom mold to be applied pressure and the base moves down being guided by the guiding means. At this time, the energizing means energizes the inner top mold to press the bottom mold, thereby corrugations for the inner part of the workpiece of the conductive damper are molded. At this time, the workpiece of the conductive damper is pulled toward the inner side thereof. Then, the base is further moved downward to press an outer top mold (i.e. the second top mold) onto the bottom mold, thereby corrugations for the outer part of the workpiece of the conductive damper are molded.
By pressing the workpiece of the conductive damper at least in two steps separately as described above, the large amount of cloth and knitted tinsel wires can be pulled into the mold. Thereby, the tensional damage applied to the knitted tinsel wires is reduced, and the endurance and the moldability of the conductive damper improve. Moreover, the press molding of the corrugation having a deep configuration is achieved to meet with the demand of producing a speaker having large oscillation amplitude.